Customarily, a variety of flushing systems are used for flushing urinals and toilets: a first type includes a float-operated intake valve, mounted at a water intake pipe, for delivering water into a water tank. The intake valve includes a rod connected to a float which, when a predefined level of water has accumulated in the tank, closes the intake valve. An outlet fixture at the bottom of the water tank discharges the water in the water tank into the toilet bowl when the flush handle is activated to flush the toilet. During and after the flushing action, the float drops below a closing position, this opens the intake valve, and water flows into the tank until it reaches the predefined level. At that point, the float is once again at the level that closes the intake valve.
A second toilet flush system uses water directly from a supply line for flushing. This flush system uses a flush valve (i.e., a “Flushometer”) that may be a diaphragm-type valve or a piston-type valve. This flush valve can be manually activated by depressing a handle (or can be automatically activated by a sensor) to control flushing a toilet or urinal. In these systems the flush valve controls a pilot section that is located somewhat above the diaphragm (in a valve diaphragm-type valve) or the piston (in a piston-type valve). The pilot section receives water through one or several control orifices. The valve controls pressure in the pilot section, which in turn activates water flow from the supply line to the toilet or urinal, thus creating the flush action.
In these diaphragm-type or the piston-type valves, the pilot section has control orifices with a quasi-fixed supply rate by virtue of maintaining a hydraulic condition known as “choked flow condition.” The pilot section also includes a drain valve, which is activated by the user handle to lower pressure in the pilot section. Upon activation of the drain valve (which has a flow-through rate much higher than the control orifice feed rate), the pilot chamber is depleted, resulting in the opening of the main flow passage that facilitates the main flushing flow. After handle release, followed by drain valve reseal, the main passage will remain open until the pilot chamber refills through the pilot orifice. The water pressure in the pilot chamber closes the main water passage to seal water flow, as described in detail in connection with FIG. 1, below. These diaphragm-type and piston-type flush valves have been described in numerous publications and patents. For example, various diaphragm-type flush valves are described in U.S. Pat. Nos. 5,125,621; 5,456,279; 6,216,730, or PCT publication WO91/17380, and the piston-type flush valve is described in U.S. Pat. No. 5,881,993.
FIG. 1 shows a prior art diaphragm-type pilot flush valve for flushing a toilet or a urinal. Flush valve 10 has a valve body with an upper body part 18 and a lower body part 16 separated by a diaphragm 12. Diaphragm 12 rests on a valve seat 14, which is at the top of an inner wall 30 of lower body part 16. The upper body part 18 has a cap 20 that clamps portion (periphery) 59 of diaphragm 12 against lower body part 16 using an upper housing 22. In the closed position, water that entered through a water inlet pipe 24 sits in an annular main chamber 26 surrounding cylindrical inner wall 30 of lower body part 16. The sealing action of diaphragm 12 does not allow the water to flow from main chamber 26 through the main passage defined by inner wall 30 into a water outlet conduit 32 to the toilet bowl. That is, diaphragm 12 seals water outlet 32 when the valve is in the closed position.
Flush valve 10 also includes a pilot chamber 36 formed by the dome 20 and diaphragm 12. Diaphragm 12 includes a control orifice 34, which enables water flow from main chamber 26 to pilot chamber 36 and thus causes pressure equalization between main chamber 26 and pilot chamber 36. When the pressure is equalized, there is a net force on diaphragm 12 from pilot chamber 36 downward onto the diaphragm since the diaphragm area in pilot chamber 36 is larger than the opposing diaphragm area in main chamber 26. The downward-oriented net force keeps the diaphragm 12 seated on valve seat 14, and thus, the valve is closed and sealing water outlet 32. A pressure-relief mechanism that lowers the water pressure in pilot chamber 36 opens flush valve 10: the pilot valve includes a pilot valve member 50 with a rod portion 58 displaceable by a plunger 56 connected to a manual flush handle 54. Pilot valve member 50 sits on a pilot seat 52 and seals against the diaphragm 12.
Depressing handle 54 causes plunger 56 to move against rod portion 58 and displacing pilot valve member 50. When pilot valve member 50 is displaced, water flows with minimal flow resistance from pilot chamber 36 near pilot seat 52 through the relief opening 49, while control orifice 34 in the diaphragm causes considerable resistance to the compensating flow from main chamber 26 through orifice 34 to pilot chamber 36. Consequently, the pressure in pilot chamber 36 decreases significantly below the pressure in main chamber 26 so that the force exerted by the pressure in pilot chamber 36 is lower than that exerted by the pressure in main chamber 26. Thus, the portion of the diaphragm plate 38 located interior to its clamped portion 59 flexes upward, rising off the main valve seat 14; this opens the valve and water flows from main chamber 26 to water outlet 32.
When a user releases flush handle 54, pilot valve 50 returns to its position on pilot valve seat 52, but the pressure in the pilot chamber 36 does not immediately return to the level in the main chamber 26 because the pressure-equalizing flow from main chamber 26 to pilot chamber 36 is restricted by the small size of control orifice 34. This delay in pressure equalization is desirable because for a predetermined length of time water flows from water outlet 32 to the connected toilet or urinal. Ultimately, however, the water flow via control orifice 34 equalizes the pressure between main chamber 26 and pilot chamber 36 to the point at which the downward force on the diaphragm overcomes the upward force, and the valve closes. This entire flushing cycle is repeated by moving handle 54.
There are several existing design approaches used for converting (i.e., retrofitting) the existing manual flush valves, such as valve 10, to sensory-activated electronically controlled automatic valves. There is a top cover assembly that replaces the upper housing 22 (shown in FIG. 1). The top cover system includes an electronic sensory module, a battery pack, and electronics for controlling a bi-stable solenoid that acts upon a pilot valve. The pilot valve in turn controls the main diaphragm valve. The top cover conversion system usually includes a new main diaphragm assembly that replaces main diaphragm 12 (used in the manual system shown in FIG. 1). These types of conversion systems are described in U.S. Pat. Nos. 5,169,118 and 5,244,179.
Another type of sensory controlled flushing device is known as a “side mount” conversion device. Examples of these are described in U.S. Pat. Nos. 5,431,181, 5,680,879 and 6,056,261. Side mount devices include a sensory module (which senses a user of the facility), a battery pack, an electric motor, and an activation plunger mounted onto a common housing. Specifically, in the “side mount” device, the activation plunger is mounted onto the flush valve assembly after first removing a manual handle (e.g., handle 54 in FIG. 1). Upon receiving a flush command from the sensory module, the electronics activate the movement of the activation plunger, thereby activating the pilot valve, which in turn starts the flush cycle.
The installation of the “side mount” conversion device to make the manual flusher automatic requires removal and replacement of its flush handle, and handle removal requires breaking the existing water seal. Specifically, to install some of these retrofit devices, a person may need to turn the water supply off, dismantle portions of the flush valve, install the device, reestablish the water seal, and then turn the water supply back on. Even if the water supply does not need to be turned off, the installation requires removal of the manual flush handle. Thus, in either case, installation requires the job to be performed by a qualified professional.
Most conversion or retrofit devices have a manual override mechanism, i.e., the ability to override the sensory control and start a flushing cycle, if the control malfunctions. These systems usually have an electrical switch that bypasses the optical sensor to electronically trigger flushing, which can be done by pushing a button, for example. However, many of these systems do not allow for a “truly” manual override if there is no electrical power available, as these electrical switches cannot work during power source failure. Therefore, such conversion devices cannot start a flushing cycle by either sensory or manual means during a power failure. There is still, therefore, a strong need for reliable devices to convert or retrofit manually-operated, currently installed flush valves used in toilet rooms.